The present invention relates to apparatus and methods for inserting an intraocular lens into an eye. More particularly, the invention relates to such apparatus and methods wherein the desired insertion of the lens is easily, controllably and effectively achieved.
An intraocular lens (IOL) is implanted in the eye, for example, as a replacement for the natural crystalline lens after cataract surgery or to alter the optical properties of (provide vision correction to) an eye in which the natural lens remains. IOLs often include an optic, and preferably at least one flexible fixation member or haptic, which extends from the optic and becomes affixed in the eye to secure the lens in position. The optic of the IOL normally includes an optically clear is lens. Implantation of such IOLs into the eye involves making an incision in the eye. Making the incision as small as possible reduces trauma and speeds healing.
IOLs are known which are foldable (deformable) so that the IOL can be inserted into the eye through an incision smaller than the diameter of the lens and subsequently permitted to unfold after it has passed through the incision. A substantial number of instruments have been devised to aid in inserting such a foldable lens into the eye. The advantages of the foldable lens in cataract removal and lens replacement are so significant that many of the lens replacement procedures are performed with folded lenses inserted into the eye, and released therein to assume their initial unfolded state.
Some of the most generally accepted insertion apparatus employ a hollow insertion tube having a diameter which permits the folded IOL to pass through the hollow space defined by the tube without permanent deformation, and a plunger assembly including a rod, often made of metal, which is moved longitudinally in the hollow space in contact with the optic of the IOL to push the IOL through the hollow space.
Several disadvantages are apparent in such insertion devices. For example, pushing, without trapping or holding, the IOL through and out of the hollow space defined by the tube can cause the IOL to be released from the insertion device without precise control, so that the released IOL may damage the eye and/or may be mispositioned in the eye. In addition, the metal rod can result in marking the surface of the optic and/or even tearing the optic, particularly when the optic is made of soft materials, such as soft elastomeric silicone polymeric materials. Also, the metal rod has a tendency to by-pass the IOL in the hollow space. That is, the rod as it is being moved distally through the hollow space may actually pass through a fold in the folded optic. If this occurs, the rod becomes ineffective to push the IOL through the hollow space. This problem has been avoided in the past by increasing the cross-sectional area of the rod. However, a rod with a large cross-sectional area presents its own problems. For example, pushing such a large rod through the hollow space can damage the IOL and/or the inserter or result in an uncontrolled release of the IOL into the eye, possibly with inserter debris being disadvantageously introduced into the eye.
Stoy et al U.S. Pat. No. 4,919,130 discloses a rod-type IOL insertion device including two separate rods. This patent discloses a cup-shaped head of soft material, such as a silicone elastomer, detachably connected at the distal end of the second rod which pushes a compressed IOL through the cannula or tube. Although this cup-shaped head may avoid scratching or tearing the lens during the pushing operation, its cup-shaped distal face does nothing to increase the control the surgeon has in releasing the IOL in the eye. In addition, this cup-shaped head is relatively short, in the axial direction, which can result in the head becoming separated from the rod in the eye. This can result in an additional procedure to remove the head from the eye, which is traumatic for the patient.
One further disadvantage of using a soft head or tip is the need to place the head or tip on the rod and then to remove it, for example, after use for disposal. Because such heads tend to be relatively small, it is often difficult and time and labor consuming to apply the head to the rod manually and to remove the head from the rod manually.
The disclosure of commonly assigned U.S. patent application Ser. No. 08/592,753 filed on even date herewith is incorporated by reference in its entirety herein.
It would be advantageous to provide IOL insertion apparatus and methods which facilitate the use of soft heads or tips to enhance the advantages of using such soft heads or tips on the rods of IOL insertion apparatus.
New apparatus for inserting IOLs and methods for inserting IOLs into eyes have been discovered. The present apparatus and methods solve one or more of the problems of the prior art systems, such as those problems noted above. The present apparatus enable the surgeon to effectively and efficiently achieve a desired degree of control as the IOL is released from the apparatus, while, at the same time, making it easier and less time and labor consuming to do so. The present invention is straightforward, easy to make and practice and involves little or no modification of existing surgical techniques. Also, the IOLs do not need to be modified to accommodate the present apparatus and methods.
In one broad aspect, the present invention comprises apparatus for inserting IOLs into an eye which include a tube defining a hollow passage, for example, through at least a portion of which a folded IOL can be moved. This tube has a port, preferably at its distal end, through which the IOL is passed from the hollow passage into an eye. An elongated member is provided which is longitudinally movable within the hollow space and has a distal end portion and a proximal end portion. A rod is also included, is longitudinally movable and has a distal end region which is coupled, preferably removably coupled, to the elongated member, for example, at the proximal end region of the elongated member. A tip is secured, preferably permanently secured, to the elongated member and extends distally from the distal end portion of the elongated member. This tip is softer, and preferably more elastic, than the distal end portion and is sized and configured so that at least a portion of the tip comes in contact with the folded IOL as the elongated member is moved distally in the hollow space. The rod and the elongated member may be made of metal, a relatively rigid or non-elastic polymeric material or combinations thereof. The elongated member preferably is made of polymeric material.
Preferably, the elongated member is made of a first polymeric material and the tip is made of a different, second polymeric material. The elongated member is preferably at least somewhat rigid, for example, more rigid then the tip, to allow effective transfer of forces from the rod to the tip.
Any suitable method may be employed to produce the tip/elongated member combination. One very useful production method is insert molding. For example, the elongated member can be formed and then included in a mold in which the tip is formed onto the distal end portion of the elongated member, for example, using conventional insert molding techniques. The elongated member preferably includes at least one through hole and a portion of the tip is located in this through hole, thereby facilitating the permanent securement of the tip to the elongated member.
In one embodiment, the elongated member defines a cavity, preferably includes a plurality of elements defining a cavity, in which the distal end region of the rod is maintained. More preferably, the plurality of elements and the distal end region of the rod are configured to facilitate the distal end region passing into the cavity as the rod is moved longitudinally toward the elongated member and to resist the distal end region passing out of the cavity as the rod is moved longitudinally away from the elongated member. For example, the plurality of elements may be adapted to flex as the distal end region is passed distally into the cavity. The distal end region of the rod may be interference-fitted or friction-fitted into the cavity. Still further, the distal end region of the rod may be threaded and the elongated member may include threads, for example, on the inner sidewall of the cavity, which matingly engage the distal end region of the rod.
In any event, the rod is coupled to the elongated member.
In another broad aspect of the present invention, apparatus for holding a folded IOL prior to insertion in an eye are provided. Such apparatus comprise a tube and a tip holder. The tube defines a hollow space in which a folded IOL is maintained prior to insertion in an eye. The tube has a port through which the IOL is passed from the hollow space into an eye. The tip holder is positioned proximally of the hollow space and is adapted to hold a tip prior to the tip being carried by a rod which is longitudinally moveable within the hollow space.
In this aspect of the invention, the tip is preferably picked up by the rod as the rod is moved distally toward the hollow space. More preferably, the tip is removed from the rod as the rod moves proximally away from the hollow space.
The tip holder preferably defines a through space substantially aligned with the hollow space and through which the rod passes prior to entering into the hollow space. The tip holder is preferably adapted to resist the tip separating from the tip holder as the rod is moved distally into the through space. More preferably, the tip holder is adapted to facilitate the removal of the tip from the rod as the rod is moved proximally away from the hollow space. For example, the tip holder may include a lip extending into the through space which is adapted to remove the tip from the rod as the rod is moved proximally from the hollow space.
In one very useful embodiment, the tube and tip holder combination further comprises a tip held by the tip holder.
IOL loading cartridges including the tube and the tip holder in accordance with the present invention, can be manufactured, for example, molded as an integral unit. This unit, which is preferably made of substantially rigid polymeric material, can be very effectively used, for example, in conjunction with a rod and hand piece, and then disposed of in a cost effective manner.
The tip in accordance with the present invention may be of any suitable configuration, provided that it functions as described herein. The tip preferably has a configuration such that (1) at least a portion of the tip is trapped or held by the IOL (the IOL may be considered to be trapped by the tip); and/or (2) the tip does not bypass the IOL during the insertion process; and/or (3) the tip does not cause significant or undue damage to the IOL. More preferably, at least two of these criteria are met, and still more preferably all three of the criteria are met.
The tip is preferably made of a polymeric material, particularly an elastomeric polymeric material, such as an elastomeric silicone polymeric material.
In one very useful embodiment, the tip is sized and configured so that at least a portion of the tip is introduced into a fold of the folded IOL as the elongated member and/or the rod is moved distally in the hollow space. More preferably, the tip is sized and configured so that at least a portion of the tip is held or trapped in a fold of the folded IOL as the elongated member and/or the rod is moved distally in the hollow space. These features of the present invention preferably result in the folded IOL being passed through the hollow space of the tube other than by pushing, even through the elongated member and/or the rod and the tip are being moved distally. The folded IOL can be considered as being carried by and/or pulled by the elongated member and/or the rod/tip combination. The advantage of this non-pushing mode of passing the IOL through the hollow space is increased control. That is, the surgeon has an increased degree of control, relative to pushing the IOL through the hollow passage, of the movement of the IOL through the hollow passage of the tube and the release of the IOL into the eye.
If an elongated member is employed, the present tip is secured, preferably permanently secured, to the elongated member. Since the elongated member preferably has sufficient length to allow easy and rapid coupling to the rod, having the tip secured, preferably permanently secured, to the elongated member greatly facilitates including the tip in the present system. Also, since it is preferred that the tip be disposed of after a single use, and, while much of the remainder of the present system is made of metal and can be reused after sterilization, the use of the elongated member/tip combination is very effective for rapid changing of the tip.
The tip preferably has a proximal end segment having an outer surface which defines a cross-sectional area which is larger than the cross-sectional area defined by the outer surface of any other segment of the tip. The proximal end segment of the tip preferably is larger in cross-sectional area than is the distal end segment of the tip. This feature, which may be considered to be a distal tapering of the tip, allows the tip to more effectively and efficiently enter a fold of the IOL and to become held or trapped by the folded IOL. A particularly useful embodiment provides that the distal end segment defines a smaller cross-sectional area than does that defined by the outer surface of the proximal end of the tip. Very effective results are obtained by providing the tip with a proximal end segment which is substantially tapered. For example, at least a portion of the tip which extends distally beyond the elongated member and/or the rod may have a generally conical or truncated conical configuration which facilitates the introduction of the tip into a fold of the folded IOL.
The tip of the present apparatus preferably is itself sufficiently elongated so that when the tip is being held in a fold of the folded IOL the optic of the IOL is not in direct contact with the elongated member and/or the rod. That is, for example, the tip has sufficient length so that the optic of the folded IOL comes in direct contact only with the tip as the elongated member and/or the rod is moved distally in the hollow space defined by the tube. This feature provides substantial benefits, for example, in that the optic is prevented from contacting the elongated member and/or the rod, which may cause scratching or tearing of the optic. Excellent results are obtained with a tip having a length in the range of about 1 mm to about 5 mm or 10 mm or about 50 mm, although other lengths may be suitable. In one embodiment, the proximal end segment of the tip is longer than all the other segments of the tip combined.
In another broad aspect of the present invention, methods for inserting an IOL into an eye are provided. These methods comprise placing an IOL in a folded condition in the tube/tip holder/tip-containing apparatus described herein; moving a rod distally relative to the tip holder to position the tip on the rod; moving the rod further distally into the hollow space defined by the tube, thereby contacting the tip and the IOL; positioning the port of the tube in proximity to or in the eye; passing the IOL through the hollow space, through the port and into the eye; passing the rod proximally; and removing the tip from the rod. The positioning of the tip on the rod and the removing of the tip from the rod preferably occur substantially automatically, for example, simply by moving the rod distally into the hollow space and then moving the rod proximally out of the hollow space.
An important advantage of the present methods is that the IOL can be passed into the eye through an incision in the eye no larger than about 3.5 mm, more preferably no larger than about 3.0 mm. Also, because the tip preferably is xe2x80x9cautomatically xe2x80x9d positioned on the rod and removed from the rod, as desired, the tedious task of manually applying and removing the tip from the rod is eliminated. This facilitates the use of the tip, and more conveniently allows the attainment of the benefits of the tip. Also, since the tip is removed after use, much of the remainder of the apparatus, for example, the rod and the hand piece, can be sterilized and reused repeatedly.
Each of the individual features of the present invention disclosed herein may be used alone or in combination with one or more other of such features, provided such features are not mutually consistent with each other. All apparatus and methods involving any such feature or combination of such features are included within the scope of the present invention.
These and other aspects of the present invention will become apparent in the following detailed description and claims, particularly when considered in conjunction with the accompanying drawings in which like parts bear like reference numerals.